TWN Info Service on Climate Change (May23/03)
16 May 2023
Third World Network

Equity Assessment of Global Mitigation Pathways in the IPCC Sixth Assessment Report

By T. Jayaraman^[1], Tejal Kanitkar^[2], and Akhil Mythri^[3]

Background

The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) relies heavily on modelled global mitigation pathways (or scenarios) based on the use of Integrated Assessment Models (IAMs). These scenarios are supposed to explore the potential and/or required changes in socio-economic,  technological, and energy-related variables to meet appropriate global warming temperature targets.

Developed countries and those advocating similar views have shown an increasing tendency, to pick out some results, especially those calling for specific emissions reduction targets, from these scenarios and urge that they be inserted into COP decisions. Some of the targets they pick are averages across scenarios, while on other occasions they pick singular values from particular scenarios. These figures and targets are sought to be inserted without paying any attention to the attendant qualifiers or nuance of where these numbers emerge from and what underlying assumptions they carry. However, it is important to assess whether, and if yes how, these scenarios incorporate the foundational principles of the United Nations Framework Convention on Climate Change (UNFCCC), namely equity and the principle of common but differentiated responsibilities and respective capabilities (CBDR&RC) for these scenarios to be relevant to the climate negotiations under the Convention. These include in particular all current and future considerations under the Paris Agreement as well.

It has now become evident, after the publication of the Working Group III Report of IPCC AR6, including the release of its databases, that such an assessment of how these scenarios fare on considerations of equity and CBDR&RC, is completely absent from the IPCC AR6 reports, especially in the report of Working Group-III as well as the Synthesis Report.  Such an equity assessment would have been of significant policy relevance. The IPCC affirms this omission with the following statement in the Summary for Policymakers of the Synthesis Report that notes: Modelled scenarios and pathways are used to explore future emissions, climate change, related impacts and risks, and possible mitigation and adaptation strategies and are based on a range of assumptions, including socioeconomic variables and mitigation options. These are quantitative projections and are neither predictions nor forecasts. Global modelled emission pathways, including those based on cost effective approaches contain regionally differentiated assumptions and outcomes, and have to be assessed with the careful recognition of these assumptions. Most do not make explicit assumptions about global equity, environmental justice or intraregional income distribution. IPCC is neutral with regard to the assumptions underlying the scenarios in the literature assessed in this report, which do not cover all possible futures.

Given the importance and significance of the foundational principles for developing countries, it is necessary that such an equity and common but differentiated responsibilities and respective capabilities (CBDR&RC) assessment of these scenarios is undertaken, by developing country scientists, even if not done so by the IPCC.

Equity Assessment of IPCC Scenarios

In this policy brief, we summarise the main findings of such an equity assessment of 556 of the 1202 scenarios used by the IPCC to arrive at its global assessments[4].

All global mitigation pathways are based on some underlying regional classification of the world as their basis. Global estimates are the result of aggregating the analyses and results based on the regional classification. The 556 model scenarios, the results of whose analyses are presented here, have an underlying 10-region classification and correspond to restricting warming levels to 1.5℃ and 2 ℃.[5]

Our results show that all scenarios taken together project a highly unequal future world that perpetuates most of the global inequalities current today. In these scenarios, the temperature goals are achieved through significant and disproportionate suppression of growth and demand, and hence energy use, in the developing world, and the remaining carbon budget is disproportionately consumed by developed countries. This equity assessment analyses scenario outcomes and the differences between developed and developing regions for the following key variables: GDP and consumption of goods and services, primary energy consumption, fossil fuel consumption, carbon dioxide removal through afforestation and carbon capture and sequestration (CCS), emission reduction rates, and implied cumulative emissions by region across scenarios.

We present here some of the key results for each set of variables:

GDP and Consumption if Goods and Services

• Even by 2050, a significant level of inequality persists in per capita GDP between developed and developing regions. In most of the developing world, per capita GDP in 2050 is restricted to the range USD 9000 to USD 28,000, while for South Asia and Sub-Saharan Africa it is restricted to even lower levels at ~USD 18,000 and ~USD 9000 respectively.

• The projected per capita GDP of developing countries in 2050 is lower than the current per capita GDP of developed countries as a whole, and much lower if compared to the current per capita GDP of OECD countries.
• The projected levels of per capita consumption of goods and services are restricted even more severely for developing regions, i.e., from $3000 and $5000 for Sub-Saharan Africa and South Asia as compared to $40,000 and $59,000 for Western Europe and North America respectively in the C1 scenarios.

Primary Energy Consumption

• Across scenarios, per capita primary energy consumption in Annex-I regions remains well above that of non-Annex-I regions, even in 2050.
• The North American region is projected to consume about 6-8 times more energy than Sub-Saharan Africa and ~5 times more energy than South Asia in 2050. These values are for total primary energy consumption, not just the consumption of fossil fuels. This implies that in these scenarios, there is a severe restriction of energy consumption, even from renewable energy sources, for non-Annex-I regions.

Fossil Fuel Consumption

• Across scenario categories, Pacific OECD and North America continue to use more coal per capita in 2050 compared to most developing regions. Sub-Saharan Africa and Latin America are projected to use zero coal by 2050.
• Across all scenarios, per capita oil and gas use in North America and Europe also continues to remain high while it is lower in Africa, South Asia, and Latin America compared to all other regions.
• The continued use of gas and oil across the global North also holds true for scenarios that project warming to remain at 1.5 deg. C with no or limited overshoot, in which global emissions reach net zero around 2050.
• The highest percentage reduction in fossil fuel use between 2020 and 2050, across all three fossil fuels, is in Sub-Saharan Africa. Across scenarios, regions of Latin America, Sub-Saharan Africa, and South Asia, are projected to have a higher share of non-fossil energy in their total primary energy mix as compared to Annex-I regions in 2050. These disproportionate reductions are over and above the considerably  lower value of per capita energy consumption in these developing regions to begin with.

Carbon Dioxide Removal from Afforestation and CCUS (Carbon Capture, Utilization and Storage)

• The absolute values, on the global scale, of CO2 sequestration from CCUS, even before net-zero, are large, ranging between 171 to 474 GtCO2 in scenarios for 1.5 deg. C warming with no to limited overshoot (50% probability) and 112 to 724 GtCO2 in scenarios for 2 deg. C warming (with > 67% probability).
• Across models, CO2 sequestration from Land Use (afforestation) varies between 9 to 163 GtCO2 in scenarios for 1.5 deg. C with no to limited overshoot (50% probability) scenarios and 4 to 191 GtCO2 in scenarios for 2 deg. C warming (with > 67% probability).
• Together total pre-net-zero carbon dioxide removal is thus projected to be ranging from a significant fraction to values even larger than the remaining carbon budget itself.
• Of the total sequestration before net zero is reached, 65% to 85% is in developing countries in scenarios for 1.5 deg. C (50% probability) scenarios, with a very similar percentage, 66% to 84%, even in 2 deg. C (> 67% probability) scenarios.

CO2 Emissions and the Global Carbon Budget

• Per capita emissions in Latin America, South Asia, and Sub-Saharan Africa remain the lowest, even by 2050, with net negative emissions in the Latin American region in 2050 in scenarios for 1.5 deg. C warming with no or limited overshoot (50% probability). Latin America reaches net zero emissions earlier as compared to any other region.
• The projected emissions reduction rates in the near term, i.e., between 2020 and 2030, are even more seriously in violation of the principles of equity and CBDR&RC. In the scenarios for 1.5 deg. C warming with no or limited overshoot (50% probability), not only do all regions start emissions reductions immediately, but the rates of emissions reduction are also higher for some developing regions (notably China+ and Sub-Saharan Africa) as compared to developed countries.
• Developed countries have appropriated and continue to consume a disproportionate share of the global carbon budget from 1850 onwards. Model scenarios perpetuate this inequity into the future by projecting a disproportionate allocation of even the remaining carbon budget to developed countries.

In conclusion, our analysis clearly shows the inequitable outcomes that underlie the summary assessments of the IPCC. As we have noted above, the IPCC itself provides only a weak qualifier for the lack of equity and the need for recognition of the underlying assumptions. However, our analysis shows much more. It exposes the fact that the regional assumptions and outcomes, and the methodologies used in these models, perpetuate stark global inequalities between the developed and developing world. These untransparent assumptions and methodologies underlie the aggregate global targets, such as global emissions reductions by 2030, mid-century net-zero years, or peaking years, currently being sought to be imposed in global climate policymaking.

Both average and singular values taken out of context from the overall scenario results of the AR6 for inclusion in COP decisions, especially immediately in the context of the GST, are untenable, as they violate the requirement of being guided by both the “best available science” as well as “equity”. Our analysis clearly underlines the need for new frameworks for emissions modelling, scenario building, and the construction of a vision of a future that foreground equity and climate justice.

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[1] M. S. Swaminathan Research Foundation, Chennai, India. Email: jayaraman@mssrf.res.in

[2] National Institute of Advanced Studies, Bengaluru, India. Email:tejalk@nias.res.in

[3] National institute of Advanced Studies, Bengaluru, India. Email:akhilmythri@nias.res.in

[4] A more detailed explanation of the methods used for this analysis and discussion of the results can be found at https://osf.io/p46ty/.

[5] There are other scenarios based on a 6-region classification of the world. However, the 10-region illustrate better our point about the drastic nature of the assumptions made, which are then hidden or covered up when only global results are cited.